Transport devices for dynamic scales are known from prior art. In such systems, the materials to be weighed are supplied in succession to a weighing belt and weighed via this belt during transport. The materials, in particular letters, are supplied to the weighing belt via an inlet area and transferred downstream of the weighing belt to a removal unit.
In the transfer of the letter in the inlet area from the supply device, which is not being weighed, to the weighing belt, which constitutes the preload, an undesired force shunting often occurs and leads to dynamic effects that interfere with the weighing signal. For a particularly precise and interference-free determination of the weight of the letter, clamping the letter laterally on the weighing belt during the weighing process is known from prior art. Such a method reduces or eliminates shocks so that a steady transfer of the letter becomes possible. Such a solution is shown, for example in DE 10 2007 044 746 A1.
Also known is the idea of transporting the letters already in the inlet area at the speed with which they are conveyed further on the weighing belt, in order to largely preclude shock effects or mass moment of inertia effects. To this end, DE 10 2005 018 395 A1 teaches clamping the materials on edge laterally between opposing conveyor belts and releasing the clamping in the area above a horizontal weighing belt, so that the materials fall onto the weighing belt and are weighed there. They are simultaneously further transported with the weighing belt and finally again clamped by the conveyor belts downstream of the scale. In this case, however, the weighing cell is influenced by considerable interfering forces. In addition, this device is not suitable for transporting letters on edge on the weighing belt.
Therefore the solutions known from prior art cannot satisfy higher requirements for weighing precision with a transport speed that is simultaneously as high as possible.